Automotive B-Pillar Design
Aim:
To create a B pillar of a car using the master section and styling surface as an input and performing Draft Analysis on the final model (3D CAD model).
Objective:
To ensure proper tree structure is followed.
Creating a tooling axis and following design rules.
Creating CLASS B and C surface using CLASS A surface as an input.
Following the master section to create flange.
Following the master section for thickness and to create the closed volume.
Following the master section to create Attachment features.
Procedure:
TOOLING AXIS:
First import the given Class A surface model of the B Pillar in CATIA V5.
After importing the model, check for the boundaries.
A tooling axis needs to be created in a direction from which it can capture most parts/features of the component. Generally a tooling axis will be created perpendicular to the base surface of the component.
In this case we need to create the tooling axis in Z - direction. So in order to create the tooling axis in Z - direction, we first need to create a reference point.
A reference point can be created using the master section 1 given as an input. Create a point using the point in between option and select the two end points of the master section DOG HOUSE which will give us a point at the center. Once we get the center point change the point in ‘between’ option to ‘coordinates’.
Now using this point create a line in Z - direction.This line will give us the tooling axis.
DRAFT ANALYSIS ON CLASS A SURFACE:
To perform Draft Analysis on the CLASS A surface, Go to menu bar > select insert > Analysis > Feature Draft Analysis.
To give draft direction, use the compass and align it with the tooling axis which we created for the model. Once it is properly aligned, select the surface of the model which will show us the draft angle given on the component. Make sure the draft angle on the component is having 3 deg draft value (component showing green in colour). If the draft value is negative (component colour in red) then we need to adjust the tooling axis direction with the help of compass.
Since there is a minor issue with CLASS A surface, a few portions of the surface are showing red in colour which means the draft angle is negative for that portion of surface. In this challenge we are ignoring that negative portion because a change in tooling direction will result in the draft analysis to fail on the final CAD model.
Note: Draft value ranging from 0 - 3 deg will show the component Blue in colour.
Using the Analysis option under Display Tab, we can check / analyze the exact draft value at any point on the given model.
CLASS B SURFACE:
To create a CLASS B surface we first need to extract the CLASS A surface. After extracting the surface, offset it to 2mm (since we know that the thickness of the component is 2 mm).
Note: The thickness of the component can be measured from the master sections.
After offsetting the surface we can observe that the CLASS B surface is having a patch / missing surface. This surface needs to be fixed by manually creating a surface.
To create a surface over the patch, we first need to extract the boundaries of that edges separately and using the “multi section” option a new surface can be created. Now join this patch surface with the offset surface to form a CLASS B surface.
FLANGE:
From the master section it can be observed that the B Pillar is having Flange but the styling surface / CLASS A surface which was given to us an input don’t have any Flange.
So in order to create a Flange on both A & B surfaces we first need to extract the boundaries of the CLASS A / B surface as shown in figure below.
After extracting the boundaries, apply a smooth option to it in order to avoid any surface continuity issues.
Surfaces of CLASS A / B which are attached to the boundary need to be extracted first which will act as a reference surface for the Flange while sweeping.
Now sweep the boundary with the reference surface (surfaces which we extracted) and give an appropriate angle such that the Flange is aligned with the master section.
Once the Flange is created, Join it with the CLASS A / B surface (Join the Flange with the surface for which it was created and aligned with the master section).
Note: The Flange needs to be created on both sides of the B pillar by following the above mentioned procedure. Flange for CLASS A and CLASS B surface needs to be created separately.
CLASS C SURFACE:
To create a CLASS C surface, first extract the boundaries (all edges separately) of the CLASS A surface (the surface with FLANGE) as shown in below figure.
After extracting the boundary, we need to perform smooth (max. Deviation as 0.001mm) operation on it in order to create a continuous tangent surface.
Now using the ‘sweep’ option create the surface. To perform this operation, Go to the Toolbar > Sweep > Profile type > Line > Subtype > With draft direction > Guide curve 1 - (select the extracted boundaries) > Draft direction - (select the tooling axis) > angle as 3 deg and give any suitable length and press ok.
Note: The boundaries of the CLASS A surface needs to be extracted separately and the sweep operation also needs to be performed separately. It is not possible to create a C surface with a single sweep following the Draft Direction.
Once these sweep surfaces are created, trim them to join the surfaces. This will give us a CLASS C surface.
FINAL TRIM :
To create the B Pillar component we need to join all these surfaces (i.e, CLASS A, B and C surfaces).
First join the CLASS A surface with the CLASS C surface and then trim this joined surface with the CLASS B surface to get the final output.
CLOSED SURFACE:
Since these surfaces are hollow, we need to close it to form a thick solid component.
Using the “CLOSE SURFACE” option in PART WORKBENCH, a solid body from the surface can be formed.
This will give us a solid component. (B Pillar without engineering features).
ENGINEERING FEATURES:
Dog house:
Dog house is an engineering feature that is used in plastic trim design. It is used as a supporting feature for other engineering features like snaps, locators etc. that are mounted on the Dog house to increase their strength and also to avoid the sink marks.
To create a Dog house we need to follow the master sections which were given to us as an input. The top surface and the supported walls of the Dog house on which the locator is laid is created by simply extracting the lines from the master section in a sketch and extruding it to a certain length as shown in figure below.
Now with the help of the master section 2 (other master section given), the wall closing the Dog house is created and another wall is created at the open end of the Dog house to split it with solid body.
These surfaces are now trimmed to form a Dog house and it is then thickened by 2mm to create a solid body.
A draft of 0.5 deg is given to the outer walls of the Dog house following the draft direction of the main tooling axis.
The inner walls of the Dog house are created at an offset value of 1.2mm from the outer walls and the top surface for the inner walls is created by intersecting the CLASS A surface with the back wall of the Dog house.
This surface is then split with the close solid to create the inner walls of the Dog House.
In order to draft the inner walls of the Dog house, a lifter axis is first created and then a 0.5 deg draft is given to it following the draft direction of the lifter tooling axis.
The Dog house is now created.
4 - way locator:
Locators are a great way to make sure the parts we are putting together fit the way we want them to fit. To create a 4 way locator, we need to create a sketch with two lines intersecting each other perpendicularly forming a ‘+’. Once the sketch is created, pad it to form a locator.
Note: The 4 - way locator is created on the top surface of the Dog house following the master section.
A draft of 0.5 deg is given to the locator and also a chamfer of 5mm at 45 angle is given to the top edges of the locators.
Once the locator is created following the master section, add it to the Dog house.
The Dog house can now be mirrored by creating a plane between the two Dog houses using the master section.
Ribs:
Ribs are created to increase the strength of a part without increasing the thickness of its walls. Because less material is required, ribs can be a much more cost-effective solution as well.
To create a rib, we first need to draw a straight line (where we want a rib) in the sketcher workbench. After creating the line, extrude it and pad it.
Since we need to create multiple ribs which are 50mm apart, first go to the CLASS A / B surface and extract the boundary/edge where the flange is connecting to the main body. Now using these boundaries, create repetition points which are at a distance of 50mm from each other.
Now copy the rib (solid body) which we created and paste it in the main tree structure. Using the translate option the copied rib can be moved from one point to another. Repeat the above step for creating all the ribs and position it on the points that we have created using the repetition points option.
Offset the CLASS B surface to 10mm and trim the ribs with it removing the excess portion of the ribs and give a draft of 0.3 to the ribs.
Once all the engineering features are created, add it /trim it to/with the main body i.e, B Pillar and give appropriate fillet value to all parts of the body.
DRAFT ANALYSIS ON FINAL MODEL:
To perform Draft Analysis on the 3D CAD model, Go to menu bar > select insert > Analysis > Feature Draft Analysis.
To give draft direction, use the compass and align it with the tooling axis which we created for the model. Once it is properly aligned, select the surface of the model which will show us the draft angle given on the component. Make sure the draft angle on the component is having 3 deg draft value (component showing green in colour).
Main tooling axis:
Lifter tooling axis:
Note: Draft value ranging from 0 - 3 deg will show the component Blue in colour.
Using the Analysis option under Display Tab, we can check / analyze the exact draft value at any point on the given model.
3D CAD MODEL:
TREE STRUCTURE:
Result:
B Pillar component with engineering features using the master section and styling surface as an input have been successfully created and draft analysis have also been performed for the same.